German Patent No. 40 03 227 describes a fuel injector which, as a valve which can be actuated electromagnetically, is provided with a magnetic circuit and a seat valve. In this valve, a fuel filter intended to keep dirt particles away from the seat region is pressed into a core at its feed end, the core serving as a fuel inlet connection. Moreover, an adjusting sleeve and a helical return spring are also arranged in the longitudinal opening of the core. The pressed-in adjusting sleeve is used to adjust the spring bias of the return spring engaged on it which is braced against the valve needle with its downstream end, pressing the valve-closure member against a valve seat in the closing direction of the valve when the magnetic coil is not excited. Thus, several component parts are fastened in the fuel inlet connection, possibly in a chip-forming manner.
Moreover, it is known from German Patent No. 41 40 070, German Patent No. 196 38 201, or from PCT Patent Publication No. WO 93/18299 to arrange filter elements in fuel injectors near the valve seat.